Metal ball fabricating apparatus

ABSTRACT

Provided is a metal ball fabricating apparatus for fabricating a metal ball by melting a material. The metal ball fabricating apparatus includes: a fabricating unit configured to fabricate a metal ball; and a collecting unit configured to collect the metal ball. The fabricating unit includes: a chamber configured to receive and store a material; a heating unit configured to apply heat to melt the material in the chamber; an orifice disposed at a lower portion of the chamber to which a metal ball droplet drops; a piston disposed over the orifice to generate a metal ball droplet; and a purifying system configured to remove a foreign substance from the material.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to Korean PatentApplication No. 10-2013-0104511, filed on Aug. 30, 2013, in the KoreanIntellectual Property Office, the disclosure of which is incorporatedherein in its entirety by reference.

FIELD OF THE INVENTION

One or more embodiments relate to metal ball fabricating apparatuses,and more particularly, to a metal ball fabricating apparatus forfabricating a metal ball by melting a material.

BACKGROUND

An orifice having an inner diameter of about 50 μm or less is used tofabricate a micro metal ball having size of about 100 μm, but an oxideof molten solder may block the orifice due to a small inner diameter ofthe orifice.

In many cases, a purifying operation for purifying a raw material in analloying process is performed to solve the problem of orifice blockage.

However, since an oxide layer exists on a lumpy surface of a lump of araw material generated in the alloying process, oxides may be againmixed in the molten solder, at the time of being input into fabricationequipment.

Therefore, there is a need to solve the problem of orifice blockage byincorporating a raw material purifying system, which is used in analloying process, into a metal ball fabricating apparatus.

SUMMARY

One or more embodiments include metal ball fabricating apparatuses forfabricating metal balls by melting materials.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

According to one or more embodiments, a metal ball fabricating apparatusfor fabricating a metal ball by melting a material includes: afabricating unit configured to fabricate a metal ball; and a collectingunit configured to collect the metal ball, wherein the fabricating unitincludes: a chamber configured to receive and store a material; aheating unit configured to apply heat to melt the material in thechamber; an orifice disposed at a lower portion of the chamber to whicha metal ball droplet drops; a piston disposed over the orifice togenerate a metal ball droplet; and a purifying system configured toremove a foreign substance from the material.

The purifying system may include a discharge pump configured todischarge a vaporized foreign substance in a heating atmosphere.

The purifying system may include a vacuum pump configured to adjust avacuum level of the chamber to below about 10⁻¹ torr.

The purifying system may include a temperature control unit configuredto adjust a heating atmosphere temperature of the chamber in a range ofabout 500° C. to about 800° C.

The piston and the orifice may be disposed to have a gap of about 0 mmto about 0.5 mm therebetween.

The fabricating unit may include a gap control unit configured tocontrol the gap between the piston and the orifice.

The orifice may include a graphite material.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings in which:

FIG. 1 illustrates an overall structure of a metal ball fabricatingapparatus according to an embodiment;

FIG. 2 illustrates a fabricating unit of a metal ball fabricatingapparatus according to an embodiment;

FIG. 3 illustrates a graph comparing wettability test results before andafter purification is performed by using a purifying system of a metalball fabricating apparatus according to an embodiment;

FIG. 4 presents a table comparing wettability test results before andafter purification is performed by using a purifying system of a metalball fabricating apparatus according to an embodiment;

FIG. 5 illustrates a state of the material for fabricating a metal ballwhen the purification temperature is about 300° C. according to anembodiment;

FIG. 6 illustrates a state of the material for fabricating a metal ballwhen the purification temperature is about 800° C. according to anembodiment;

FIG. 7 illustrates a state of the material when the vacuum level isabout 10⁻¹ torr according to an embodiment;

FIG. 8 illustrates a state of the material when the vacuum level isabout 10⁻³ torr according to an embodiment;

FIG. 9 illustrates a comparison of the test dimension and result foreach material of the orifice provided in a fabricating unit of a metalball;

FIG. 10A illustrates a droplet when a metal orifice is used;

FIG. 10B illustrates a droplet when a ceramic orifice is used;

FIG. 10C illustrates a droplet when a graphite orifice is used;

FIG. 11A illustrates a comparison between results when a metal nozzle isused;

FIG. 11B illustrates comparison between results when a ceramic nozzle isused;

FIG. 11C illustrates a comparison between results when a graphite nozzleis used;

FIG. 12 is a table illustrating an overall comparison between resultswhen each of the vacuum level, the purification temperature, and thefabrication temperature is changed; and

FIG. 13 illustrates a graph comparing uniformities of metal ball sizesdepending on gaps between a piston and the orifice provided in afabricating unit of a metal ball fabricating apparatus according to anembodiment.

FIG. 14 presents a table comparing uniformities of metal ball sizesdepending on gaps between a piston and the orifice provided in afabricating unit of a metal ball fabricating apparatus according to anembodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout. In this regard, the presentembodiments may have different forms and should not be construed asbeing limited to the descriptions set forth herein. Accordingly, theembodiments are merely described below, by referring to the figures, toexplain aspects of the present description. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

Exemplary embodiments will now be described in detail with reference tothe accompanying drawings. However, these embodiments are not limitedthereto.

The effects and features of the embodiments and the accomplishing methodthereof will become apparent from the following description of theembodiments, taken in conjunction with the accompanying drawings. Theinvention may, however, be embodied in many different forms and shouldnot be construed as being limited to the embodiments set forth herein;rather, these embodiments are provided such that this disclosure will bethorough and complete, and will fully convey the concept of theinvention to one of ordinary skill in the art.

Spatially relative terms, such as “above,” “upper,” “beneath,” “below,”“lower,” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the drawings. It will be understood thatthe spatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation illustrated in the drawings. For example, if the device inthe drawings is turned over, elements described as “below” or “beneath”other elements or features would then be oriented “above” the otherelements or features. Thus, the exemplary term “above” may encompassboth an orientation of above and below. The device may be otherwiseoriented (rotated about 90 degrees or at other orientations) and thespatially relative descriptors used herein may be interpretedaccordingly.

The terminology used herein is for the purpose of describing theembodiments only and is not intended to be limiting of the embodiments.As used herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprise” and“comprising” used herein specify the presence of stated elements, steps,operations, and/or devices, but do not preclude the presence or additionof one or more other elements, steps, operations, and/or devices.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which the embodiments belong. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

FIG. 1 illustrates an overall structure of a metal ball fabricatingapparatus 1 according to an embodiment. FIG. 2 illustrates a fabricatingunit 10 of the metal ball fabricating apparatus 1 according to anembodiment. FIGS. 3 and 4 illustrate a comparison between wettabilitytest results before and after purification is performed by using apurifying system 30 of the metal ball fabricating apparatus 1 accordingto an embodiment. FIGS. 5 and 6 illustrate a comparison between resultswhen purification is performed under different purification temperaturesby using the purifying system 30 of the metal ball fabricating apparatus1 according to an embodiment. FIGS. 7 and 8 illustrate a comparisonbetween results when purification is performed under different vacuumlevels by using the purifying system 30 of the metal ball fabricatingapparatus 1 according to an embodiment. FIGS. 9 to 11 illustrate acomparison between results when an orifice 150 provided in thefabricating unit 10 of the metal ball fabricating apparatus 1 accordingto an embodiment is formed of different materials. FIG. 12 is a tableillustrating an overall comparison between results when each of thevacuum level, the purification temperature, and the fabricationtemperature is changed. FIGS. 13 and 14 illustrate a comparison betweenuniformities of metal ball (S) sizes depending on gaps between a piston130 and the orifice 150 provided in the fabricating unit 10 of the metalball fabricating apparatus 1 according to an embodiment.

The metal ball fabricating apparatus 1 according to an embodiment is ametal ball fabricating apparatus 1 for fabricating a metal ball S bymelting a material. The metal ball fabricating apparatus 1 includes: afabricating unit 10 configured to fabricate a metal ball S; and acollecting unit 20 configured to collect the metal ball S. Thefabricating unit 10 includes: a chamber 110 configured to receive andstore a material; a heating unit 120 configured to apply heat to meltthe material in the chamber 110; an orifice 150 disposed at a lowerportion of the chamber 110 to which a metal ball (S) droplet drops; apiston 130 disposed over the orifice 150 to generate a metal ball (S)droplet; and a purifying system 30 configured to remove a foreignsubstance from the material.

The metal ball fabricating apparatus 1 is configured to include thefabricating unit 10 and the collecting unit 20.

The fabricating unit 10 includes various devices configured to receive amaterial, which is a raw material of the metal ball S, and fabricate themetal ball S, and substantially constitutes a body of the metal ballfabricating apparatus 1. The metal ball S may be a metal ball S used ina wire bonding package and may be spherical; however, embodiments arenot limited thereto.

The material used to fabricate the metal ball may be, for example, analloy including various metals such as copper (Cu), nickel (Ni),aluminum (Al), and cobalt (Co), and a chemical additive may be addedthereto; however, embodiments are not limited thereto.

The material is stored in the chamber 110. In one embodiment, thechamber 110 is configured to have a predetermined strength to endure ahigh temperature and a high pressure difference, and has an appropriatecapacity.

The heating unit 120 is provided to heat the material in the chamber110. The heating unit 120 may heat the chamber 110 by, for example, anelectrical resistance to melt the material in the chamber 110, but itsconfiguration and shape are not limited thereto.

The orifice 150 is provided at a lower portion of the chamber 110 sothat the material in the chamber 110 may be heated and melted and themelted material may drop in the shape of droplets. The orifice 150 hasthe shape of a minute pipe and has an appropriate shape andconfiguration for forming a metal ball (S) droplet of a desired size andcontrolling the metal ball (S) droplet. Since the orifice 150 may bedamaged when the melted metal ball (S) droplet drops, the orifice 150may be attached/detached to/from the chamber 110 so that the orifice 150may be replaced when necessary; however, embodiments are not limitedthereto. The orifice 150 may be configured to include a graphitematerial.

The piston 130 is disposed over the orifice 150. The piston 130 isspaced apart from the orifice 150 by a predetermined gap and isconfigured to perform a piston movement so that the melted materialforms the metal ball (S) droplet. Accordingly, the piston 130 may beconfigured to perform a vertical piston movement, and the gap betweenthe piston 130 and the orifice 150 and the movement period of the piston130 may be adjusted appropriately. A power applying unit 140 may beprovided so that the piston 130 may perform a piston movement.

The purifying system 30 is provided to remove a foreign substance fromthe material stored in the chamber 110. The purifying system 30 mayinclude a device constituting a portion of the fabricating unit 10 ofthe metal ball fabricating apparatus 1. The purifying system 30 may beany member or device that may serve to remove a foreign substance fromthe material. It may also be understood that, when the purifying system30 constitutes a portion of the fabricating unit 10, the purifyingsystem 30 may be incorporated into the fabricating unit 10 to remove aforeign substance from the material in a fabrication process. Thepurifying system 30 will be described later.

In addition to the above-described units or members, an inert gasinjecting unit 160, various pipe structures, and valve units 162 and 172may be provided to supply an inert gas to maintain an atmospheresuitable for fabricating the metal ball S; however, embodiments are notlimited thereto.

The collecting unit 20 is provided to collect the metal ball Sfabricated by the fabricating unit 10. The collecting unit 20 mayinclude a collecting valve 24, a collecting chamber 26, and a coolingchamber 22 configured such that the metal ball (S) droplet droppingthrough the orifice 150 may be cooled and solidified in a droppingprocess.

The cooling chamber 22 may be extended with a vertical height such thatthe metal ball (S) droplet may be cooled in the dropping process.

The collecting chamber 24 is a member for collecting the dropped metalball (S). A sieve may be provided in the collecting chamber 24 to loadthe metal ball S. The sieve may be extracted by a transport unit todischarge the metal ball S to outside.

The collecting unit 20 may include various transport devices forcollecting the metal ball S and a valve serving to collect the metalball S, and the configuration of the collecting unit 20 is not limitedthereto.

Hereinafter, the purifying system 30 will be described in detail.

The purifying system 30 may include any device that is used to remove aforeign substance from the material and may also include any device thatmay serve to remove a foreign substance from the material.

For example, when the material is heated to a predetermined temperatureto remove the foreign substance, the heating unit 120 heating thematerial may serve to remove the foreign substance, but the heating unit120 may also be used to melt the material that is used to fabricate themetal ball S. As another example, a gas injecting unit and a pumpserving to discharge a vaporized foreign substance may serve to removethe foreign substance and constitute a portion of the purifying system30. However, since the gas injecting unit and the pump may also serve toadjust an atmosphere in the chamber 110, melt the material, andfabricate the metal ball S, they may also be included in a componentother than the purifying system 30.

Thus, according to some embodiments, the purifying system 30 should notbe regarded as a separate device that is independent of other members ordevices in the fabricating unit 10, and may be regarded as a portionconstituting the fabricating unit 10.

The purifying system 30 includes a discharge pump 170 configured todischarge the foreign substance in a heating atmosphere.

When the chamber 110 is heated in a predetermined atmosphere to atemperature that is equal to or higher than a melting temperature, thematerial in the chamber 110 is melted into liquid. In this case, oxygenand a foreign substance, such as various oxides, which are contained inthe liquid material, may be floated on a surface thereof, and theforeign substance may be removed by the operation of the discharge pump170.

In this case, the atmosphere in the chamber 110 may be a near-vacuumatmosphere, and the discharge pump 170 may include a vacuum pump. By theoperation of the discharge pump 170, air in the chamber 110 may flowtoward the vacuum pump to be discharged to outside, and a relativelylight foreign substance such as the oxide may be discharged according tothe air flow. In this case, the vacuum level of the chamber 110 may below and may be adjusted to about 2.0×10⁻² torr or less.

The purifying system 30 may include a temperature control unit (notillustrated) configured to adjust a heating atmosphere temperature ofthe chamber 110 in a range of about 500° C. to about 900° C.

The temperature control unit may control the operation of the heatingunit 120 and adjust the temperature of the chamber 110 so that theforeign substance may be easily separated while the material is easilymelted. In this case, the temperature control unit may control thetemperature of the chamber 110 from about 500° C. to about 900° C., forexample, or to about 800° C. Accordingly, the temperature control unitmay include a temperature sensor and a control unit controlling theoperation of the heating unit 120.

As described above, according to the one or more of the aboveembodiments, since the purifying system 30 is included in thefabricating unit 10, the metal ball fabricating apparatus 1 mayfabricate the metal ball S by a pure material alone by removing aforeign substance from the material used to fabricate the metal ball S.Also, since a material purifying operation is performed in a meltingprocess for fabrication, a separate independent purifying unit may notbe necessary and the purified material may be prevented from beingcontaminated again by being exposed to outside when supplied into thechamber 110.

Thus, the higher-quality metal ball S may be fabricated, and theefficiency of the fabrication process may be improved and thefabrication cost may be reduced, since the blockage of the orifice 150,to which the metal ball (S) droplet drops, is prevented.

In one embodiment, the piston 130 and the orifice 150 are disposed tohave a gap of about 0 mm to about 0.5 mm therebetween.

The piston 130 is spaced apart from the orifice 150 by a predeterminedgap and performs a piston movement so that the melted material may dropin the form of droplets through the orifice 150. In this case, in orderto form a metal ball (S) droplet of a desired size, the piston 130 andthe orifice 150 may have a gap therebetween and the gap between thepiston 130 and the orifice 150 may be adjusted to about 0 mm to about0.5 mm. Herein, the gap between the piston 130 and the orifice 150represents a gap at which the piston 130 is advanced to maximum and ismost adjacent to the orifice 150.

A gap control unit 142 may be provided to adjust the gap between thepiston 130 and the orifice 150.

The gap control unit 142 may be provided to adjust the gap between thepiston 130 and the orifice 150, and may be, for example, a device thatchanges the initial position of the piston 130. By the gap control unit142, the gap between the piston 130 and the orifice 150 may be changedand the size of the metal ball (S) droplet may also be changedappropriately. Thus, the metal balls S of various sizes may befabricated according to purposes, and the general purpose of the metalball fabricating apparatus 1 may be improved.

Hereinafter, the effects of the metal ball fabricating apparatus 1according to an embodiment will be described with reference to thedrawings.

FIGS. 3 and 4 illustrate a comparison between wettability test resultsbefore and after purification is performed by using the purifying system30 of the metal ball fabricating apparatus 1 according to an embodiment.

It may be seen from FIGS. 3 and 4 that a wetting force is increased anda zero-cross time is reduced after the purification is performed.

That is, the zero-cross time is the time taken to balance the waterlevel of solder, and the zero-cross time may be short as much aspossible. In one embodiment, in order to reduce the zero-cross time, thesurface tension should be low. In general, as the amount of interposerin a melted metal increases, the surface tension increases and thus thezero-cross time increases.

According to some embodiments, the zero-cross time is reduced after thepurification, and this may be regarded as the improvement of a fluidflow. Thus, it may be seen that the fluidity of the melted materialpassing through the hole of the orifice is improved by the purificationof the material.

Also, as the surface tension decreases, the wetting force increases. Asseen from FIG. 4, the increase of the wetting force after purificationrepresents the decrease of the surface tension, and this represents theimprovement of the fluidity of the material.

FIGS. 5 and 6 illustrate a comparison between results when purificationis performed under different purification temperatures by using thepurifying system 30 of the metal ball fabricating apparatus 1 accordingto an embodiment. FIGS. 7 and 8 illustrate a comparison between resultswhen purification is performed under different vacuum levels by usingthe purifying system 30 of the metal ball fabricating apparatus 1according to an embodiment.

FIG. 5 illustrates a state of the material when the purificationtemperature is about 300° C., and FIG. 6 illustrates a state of thematerial when the purification temperature is about 800° C. It may beseen that the oxide layer formed on the surface of the material may befurther reduced in the case where the purification temperature is about800° C., in comparison with the case where the purification temperatureis about 300° C.

FIG. 7 illustrates a state of the material when the vacuum level isabout 10⁻¹ torr, and FIG. 8 illustrates a state of the material when thevacuum level is about 10⁻³ torr. It may be seen that the oxide layerformed on the surface of the material may be further reduced in the casewhere the vacuum level is about 10⁻³ torr, in comparison with the casewhere the vacuum level is about 10⁻¹ torr.

As described above, it may be seen that the purification of the materialis further improved by the removal of the oxide when the material ismelted while the high temperature and the low vacuum level aremaintained.

FIGS. 9 to 11 illustrate a comparison between results when the orifice150 provided in the fabricating unit 10 of the metal ball fabricatingapparatus 1 according to an embodiment is formed of different materials.

FIG. 9 illustrates the test dimension and result for each material ofthe orifice 150, FIG. 10 illustrates each orifice 150, and FIG. 11illustrates the uniformity of droplets generated through each orifice150.

FIG. 10A illustrates a droplet when a metal orifice 150 is used, FIG.10B illustrates a droplet when a ceramic orifice 150 is used, and FIG.10C illustrates a droplet when a graphite orifice 150 is used.

It may be seen from FIGS. 9 to 11 that, when the orifice 150 is formedof graphite having excellent slippage characteristics, most stable anduniform droplets are formed even when a small orifice 150 is used.

FIG. 12 is a table illustrating an overall comparison between resultswhen the vacuum level, the purification temperature, and the fabricationtemperature are changed. It may be seen from FIG. 12 that thefabrication result is varied when each of the vacuum level, thepurification temperature, and the fabrication temperature is changed.

FIGS. 13 and 14 illustrate a comparison between uniformities of metalball (S) sizes depending on gaps between the piston 130 and the orifice150 provided in the fabricating unit 10 of the metal ball fabricatingapparatus 1 according to an embodiment.

As illustrated in FIGS. 13 and 14, it may be seen that the size of thefabricated metal ball S and the deviation of the size increase as thegap between the piston 130 and the orifice 150 increases in the pistonmovement having the same frequency.

As described above, since the gap control unit 142 is provided to adjustthe gap between the piston 130 and the orifice 150, the gap between thepiston 130 and the orifice 150 may be adjusted, and the piston 130 andthe orifice 150 may be adjusted to have an optimum gap therebetween inthe fabrication process. Therefore, the metal balls S may be fabricatedto have a uniform size.

As described above, according to the one or more of the aboveembodiments, since the purifying system 30 is included the fabricatingunit 10, the metal ball fabricating apparatus 1 may fabricate the metalball S by a pure material alone by removing a foreign substance from thematerial used to fabricate the metal ball S. Also, since a materialpurifying operation is performed in a melting process for fabrication, aseparate independent purifying unit may not be necessary and thepurified material may be prevented from being contaminated again bybeing exposed to outside when supplied into the chamber 110.

Thus, the higher-quality metal ball S may be fabricated, and theefficiency of the fabrication process may be improved and thefabrication cost may be reduced, since the blockage of the orifice 150,to which the metal ball (S) droplet drops, is prevented.

Also, since the gap control unit is provided to adjust the gap betweenthe piston 130 and the orifice 150, the gap between the piston 130 andthe orifice 150 may be changed and the size of the metal ball (S)droplet may also be changed appropriately. Thus, the metal balls S ofvarious sizes may be fabricated according to purposes, and the generalpurpose of the metal ball fabricating apparatus 1 may be improved.

Also, even when a small orifice including a graphite material is used,stable and uniform metal ball droplets may be formed.

It should be understood that the exemplary embodiments described hereinshould be considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments.

While one or more embodiments have been described with reference to thefigures, it will be understood by those of ordinary skill in the artthat various changes in form and details may be made therein withoutdeparting from the spirit and scope as defined by the following claims.

What is claimed is:
 1. A metal ball fabricating apparatus forfabricating a metal ball by melting a material, the metal ballfabricating apparatus comprising: a fabricating unit configured tofabricate a metal ball; and a collecting unit configured to collect themetal ball, wherein the fabricating unit comprises: a chamber configuredto receive and store a material; a heating unit configured to apply heatto melt the material in the chamber; an orifice disposed at a lowerportion of the chamber to which a metal ball droplet drops; a pistondisposed over the orifice to generate a metal ball droplet; and apurifying system configured to remove a foreign substance from thematerial.
 2. The metal ball fabricating apparatus of claim 1, whereinthe purifying system comprises a discharge pump configured to dischargea vaporized foreign substance in a heating atmosphere.
 3. The metal ballfabricating apparatus of claim 1, wherein the purifying system comprisesa vacuum pump configured to adjust a vacuum level of the chamber tobelow about 10⁻¹ torr.
 4. The metal ball fabricating apparatus of claim1, wherein the purifying system comprises a temperature control unitconfigured to adjust a heating atmosphere temperature of the chamber ina range of about 500° C. to about 800° C.
 5. The metal ball fabricatingapparatus of claim 1, wherein the piston and the orifice are disposed tohave a gap of about 0 mm to about 0.5 mm therebetween.
 6. The metal ballfabricating apparatus of claim 5, wherein the fabricating unit comprisesa gap control unit configured to control the gap between the piston andthe orifice.
 7. The metal ball fabricating apparatus of claim 1, whereinthe orifice comprises a graphite material.